The development of intermodal transportation has created a need for improved apparatus for handling of empty trailer chassis. In this method of transportation, cargo is shipped in large rectangular containers carried on ships, railroad flat cars, and on specially designed trailer chassis which are pulled over highways in the same manner as ordinary fixed body semitrailer vans. Containers are frequently delivered by truck to a rail yard or seaport where they are unloaded and transferred to a ship or train. It may be readily seen that large numbers of empty trailer chassis may become accumulated at such transfer sites, creating a storage space problem.
One approach to reducing the space required for storing empty trailer chassis has been to stack them on top of one another. This requires lifting the chassis off the ground, turning alternate ones of the chassis upside down to enable stacking, and moving them into position for stacking. These operations have been carried out by use of forklift vehicles with chains, but this approach is cumbersome, dangerous, and requires the coordinated efforts of several people.
A forklift attachable apparatus performing the required maneuvers for stacking trailer chassis is described in U.S. Pat. No. 4,664,576, issued May 12, 1987, to Coe. This apparatus uses a pair of pivotally mounted arms including fixed and movable jaws for grasping the chassis, the jaws being mounted on a rotatable carrier. Rotation of the carrier to invert a chassis by this apparatus requires application of hydraulic power in addition to the power normally supplied to forklift arms. Components required for the hydraulic system as well as required electrical controls and gears contribute greatly to the complexity and cost of this apparatus. While this apparatus provides an advantage in that grasping and releasing of a chassis may be carried out by actuation of switches without requiring an operator to manually connect clamps or the like, this benefit is realized only by inclusion of costly and complex features. An apparatus that provides effective and safe operation without requiring power to operate its grasping and rotating mechanisms or electrical components, gears, and the like to control these mechanisms would be highly desirable and would provide overall advantages even though a small amount of manual intervention on the part of the operator would be required.